Mechanism for positioning a rotatable spindle at a predetermined angular setting

ABSTRACT

Mechanism for positioning a spindle such for example as the work spindle of a lathe at a predetermined angular setting. The mechanism is of the kind comprising an annular cam on the spindle having two helically extending surfaces meeting in the high and low points of the cam, and a cam actuator movable longitudinally relative to the spindle onto one or other of the surfaces. Thereafter continued movement of the actuator is adapted to move the cam and spindle angularly until the actuator engages a recess in the cam at its lowest point to locate the spindle against further angular movement. The mechanism is characterised by a lever pivotally mounted within a recess in the cam and urged angularly by resilient means into contact with a stop. The lever has a nose extending from the cam and terminating in a tip which is offset with respect to both the high point of the cam and the pivot axis of the lever. The arrangement is such that should the actuator first contact one side of the lever the lever will act as an extension of the cam to enable the actuator to move down this side of the lever whilst moving the cam angularly until the actuator reaches one of the aforesaid surfaces of the cam. However, in the event of the actuator first contacting the tip or other side of the lever the lever will move angularly against the resilient means to enable the actuator to contact the other surface of the cam.

United States Patent [19] Gilbert et al.

[ July 23, 1974 MECHANISM FOR POSITIONING A ROTATABLE SPINDLE AT A PREDETERMINED ANGULAR SETTING Inventors: Harold James Gilbert; Malcolm Robert Holt, both of Coventry, England [73] Assignee: Hickman Machine Tool Sales Limited, Coventry, England 221 Filed: Mar. 22, 1973 21 Appl. No; 343,676

Primary Examiner-Francis S. Husar Assistant Examiner-W. R. Briggs [57] ABSTRACT Mechanism for positioning a spindle such for example as the work spindle of a lathe at a predetermined angular setting. The mechanism is of the kind comprising an annular cam on the spindle having two helieally extending surfaces meeting in the high and low points of the cam, and a cam actuator movable longitudinally relative to the spindle onto one or other of the surfaces. Thereafter continued movement of the actuator is adapted to move the cam and spindle angularly until the actuator engages a recess in the cam at its lowest point to locate the spindle against further angular movement. The mechanism is characterised by a lever pivotally mounted within a recess in the cam and urged angularly by resilient means into contact with a stop. The lever has a nose extending from the cam and terminating in a tip which is offset with respect to both the high point of the cam and the pivot axis of the lever. The arrangement is such that should the actuator first contact one side of the lever the lever will act as an extension of the cam to enable the actuator to move down this side of the lever whilst moving the cam angularly until the actuator reaches one of the aforesaid surfaces of the cam. However, in the event of the actuator first contacting the tip or other side of the lever the lever will move angularly against the resilient means to enable the actuator to contact the other surface of the cam.

1 Claim, 3 Drawing Figures PATENTEUJULZBIHM 3. 824.884

sneer 1 (If 2 MECHANISM FOR POSITIONING A ROTATABLE SPINDLE AT A PREDETERMINED ANGULAR SETTING This invention relates to mechanism for positioning a spindle such, for example as the work spindle of a lathe at a predetermined angular setting, the mechanism being of the kind comprising an annular cam on the spindle having two helically extending surfaces meeting in the high and low points of the cam, and a cam actuator movable longitudinally relative to the spindle into contact with one or other of the surfaces and thereafter by continued movement adapted to move the cam and spindle angularly until the actuator engages a recess in the cam at its low point to locate the spindle against further angular movement.

In such mechanism it is possible for the spindle to come to rest at an angular position such that the actuator would contact the high point of the cam, and thereby prevent camming of the spindle to the located position. In order to overcome this difficulty it has been proposed to employ a second cam having a high point which is longitudinally and angularly spaced from the high point of the first mentioned cam, and to move the actuator first in one direction into contact with the second cam, to ensure that on subsequent movement of the actuator in the other direction into contact with the first cam it will not contact the high point of the latter.

The object of the present invention is to provide an improved and simplified means of ensuring that the actuator will not contact the high point of the cam.

According to the invention mechanism of the kind specified is characterised by a lever pivotally mounted within a recess in the cam and urged angularly by resilient means into contact with a stop, said lever having a nose extending from the cam and terminating in a tip which is offset with respect to both the high point of the cam and the pivot axis of the lever, the arrangement being such that should the actuator first contact the one side of the lever, the lever will act as an extension of the cam to enable the actuator to move down this side of the lever whilst moving the cam angularly until the actuator reaches one of said surfaces of the cam, whilst in the event of the actuator first contacting the tip or other side of the lever the lever will move angularly against the resilient means to enable the actuator to contact the other surfaceof the cam.

An example of the invention will now be described in its application to a multi-spindle lathe, and with reference to the accompanying drawings in which,

FIG. 1 is a diagrammatic sectional side view through a drum and one of the work spindles mounted therein,

FIG. 2 is an enlarged view of the cam and associated mechanism shown in FIG. 1, and

FIG. 3 is a fragmentary cross section through the drum to the same scale as FIG. 2.

Referring to the drawings, there is provided an intermittently rotatable drum mounted within a fixed housing 11. Within the drum are mounted a plurality of equi-angularly spaced work spindles one only of which is seen at 12; the work spindles being rotatable about their own axes in known manner, and each having an associated brake and clutch mechanism (not shown). On each spindle 12 is mounted a sleeve 13 one end of which constitutes an annular cam profile 14 formed by two oppositely directed helically extending surfaces 14a, 14b meeting in a high point 14c, and a low point at which is fomied a recess 15. In the sleeve 13 is fomied a recess 16 within which a substantially L- shaped lever 17 is mounted for angular movement upon a pivot 18. A spring pressed plunger 19 in the sleeve normally urges the lever 17 into the position shown in full lines in FIG. 2, in which a flat edge of the lever is in contact with a part 20 of the wall of the recess which constitutes a stop to limit further angular movement of the lever in this direction. The lever 17 has a nose 17a which extends beyond the cam profile 14 and terminates in a tip 17b which is offset angularly both from the high point of the cam profile and from the axis of the pivot 18. Moreover, the edge of the nose 17a at the side furthest from the pivot 18 is shaped to constitute an extension of the cam surface 14a which extends beyond the high point 140 of the cam profile.

The drum 10 incorporates a number of peripheral recesses 21 equal in number and angular spacing to the plurality of spindles 12. Within each recess 21 is a cylinder 22 containing a piston mounted upon a piston rod 23 extending through both ends of the cylinder and secured relative to the drum 10. Clamped to the cylinder 22 is a split collar 24 in which is secured a pin 25 extending through a block 26 slidable within a slot formed in a web 10a of the drum; the outer end of the pin at the opposite side of the block 26 carrying an actuating roller 27 positioned to make contact with the cam profile 14 when the cylinder 22 is moved to the left as viewed in FIG. 1, and thereby impart angular movement to the spindle 12.

The purpose and construction of the mechanism thus far described will be better understood from the following description of the working of the lathe.

It is sometimes required to effect an operation such for example as a cross drilling upon workpieces carried by the work spindles. This necessitates that the workpieces should be brought to rest at a predetermined angular position, and for this purpose the workpieces are secured to the work spindles in a predetermined angular relationship. As the drum 10 is indexed to bring each spindle and workpiece in turn into a position in which this operation is to be performed, the clutch and brake associated with the spindle are disengaged and applied respectively to bring a spindle 12 to rest. It will be appreciated that the angular position at which the spindle comes to rest initially cannot be predetermined, and to ensure that the spindle will be located at the predetermined angular position the mechanism previously described operates as follows. After the spindle has been brought to rest fluid is applied to the cylinder 22 to move the roller 27 to the left as viewed in FIGS. 1 and 2. In many instances the roller 27 will first contact one or other of the surfaces 14a or 14b so that continued movement of the roller 27 to the left will impart angular movement to the spindle 12 until the roller enters the recess 15 to locate the spindle against further angular movement. However, should the spindle initially stop in a position in which the roller 27 will first contact the nose 17a of the lever one or other of the following effects will be achieved. If the roller first contacts the edge 170 of the lever the roller will ride down this edge on to the surface 140 whilst moving the cam angularly thereby passing the high point 14c of the cam profile.

If on the other hand the roller first contacts the tip 17b of the lever as shown in FIG. 2, or contacts the nose 17a at a position slightly below the tip 17b as viewed in F IG. 2, continued movement of the roller to the left will cause the lever 17 to be rocked towards the alternative position shown in dotted lines in FIG. 2, to enable the roller to first contact the cam profile on the surface 14b. The lever 17 thereby forms a simple and efficient means of preventing the roller 27 contacting the high point 14c of the cam profile in a position in which camming might be impossible.

We claim:

1. Mechanism for positioning a spindle at a predetermined angular setting, the mechanism comprising an annular cam on the spindle, two helically extending surfaces on the cam meeting in the high and low points of the cam, a recess in the cam at its low point, a cam actuator movable longitudinally relative to the spindle into contact with one or other of the surfaces and adapted to move the cam and spindle angularly thereafter by continued movement until the actuator engages said recess in the cam to locate the spindle against further angular movement, a lever pivotally mounted with the cam, a stop for cooperation with the lever, resilient means urging the lever angularly into contact with the stop, a nose on said lever extending beyond the cam surface and terminating in a tip which is ofiset with respect to both the high point of the cam and the pivot axis of the lever, said nose being positioned on the lever such that a force applied to the tip or other side of the lever creates a moment about the pivot point of the lever, so that should the actuator first contact the one side of the lever, the lever will act as an extension of the cam to enable the actuator to move down this side of the lever whilst moving the cam angularly until the actuator reaches one of said surfaces of the cam. whilst in the event of the actuator first contacting the tip or other side of the lever the lever will move angularly against the resilient means to enable the actuator to contact the other surface of the cam.

* t 1F k UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. g Dated July 2'3, 197M Inventor) Harold James Gilbert t 1 above-identified patent It is certified that error appears in the own below:

and that said Letters Patent are hereby corrected as sh The Assignee should be wickman Machine Tool Sales Limited rather than Hickman Machine Tool Sales Limited.

Signed and sealed this 3rd day of December 1974.

(SEAL) Attest:

MCCOY M. GIBSON JR. Attesting Officer C. MARSHALL DANN Commissioner of Patents FORM PO-IOSO (10-69) uscoukhoc emnbpea i as GOVIIIHIINT FIINTIIG orncr nu o-au-su 

1. Mechanism for positioning a spindle at a predetermined angular setting, the mechanism comprising an annular cam on the spindle, two helically extending surfaces on the cam meeting in the high and low points of the cam, a recess in the cam at its low point, a cam actuator movable longitudinally relative to the spindle into contact with one or other of the surfaces and adapted to move the cam and spindle angularly thereafter by continued movement until the actuator engages said recess in the cam to locate the spindle against further angular movement, a lever pivotally mounted with the cam, a stop for co-operation with the lever, resilient means urging the lever angularly into contact with the stop, a nose on said lever extending beyond the cam surface and terminating in a tip which is offset with respect to both the high point of the cam and the pivot axis of the lever, said nose being positioned on the lever such that a force applied to the tip or other side of the lever creates a moment about the pivot point of the lever, so that should the actuator first contact the one side of the lever, the lever will act as an extension of the cam to enable the actuator to move down this side of the lever whilst moving the cam angularly until the actuator reaches one of said surfaces of the cam, whilst in the event of the actuator first contacting the tip or other side of the lever the lever will move angularly against the resilient means to enable the actuator to contact the other surface of the cam. 